Re: [PATCH v2] fs/buffer: Convert return type int to vm_fault_t

[Souptick Joarder]

On Mon, Jul 30, 2018 at 8:31 PM, Souptick Joarder <jrdr.linux@xxxxxxxxx> wrote:
> Return type of block_page_mkwrite() is converted to
> vm_fault_t type. The caller of block_page_mkwrite
> inside fs/nilfs2 nilfs_page_mkwrite converted accordingly.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
> ---
> v2: Address Jens's comment. Remove ret variable
>     from block_page_mkwrite().

I am dropping this for now. This will be merged with another
patch and I will resend it.

>
>  fs/buffer.c                 | 16 ++++++++--------
>  fs/nilfs2/file.c            | 13 ++++++++-----
>  include/linux/buffer_head.h |  2 +-
>  3 files changed, 17 insertions(+), 14 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index cabc045..aeed99f 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -2444,21 +2444,21 @@ int block_commit_write(struct page *page, unsigned from, unsigned to)
>   * Direct callers of this function should protect against filesystem freezing
>   * using sb_start_pagefault() - sb_end_pagefault() functions.
>   */
> -int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
> +vm_fault_t block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
>                          get_block_t get_block)
>  {
>         struct page *page = vmf->page;
>         struct inode *inode = file_inode(vma->vm_file);
>         unsigned long end;
>         loff_t size;
> -       int ret;
> +       int err;
>
>         lock_page(page);
>         size = i_size_read(inode);
>         if ((page->mapping != inode->i_mapping) ||
>             (page_offset(page) > size)) {
>                 /* We overload EFAULT to mean page got truncated */
> -               ret = -EFAULT;
> +               err = -EFAULT;
>                 goto out_unlock;
>         }
>
> @@ -2468,18 +2468,18 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
>         else
>                 end = PAGE_SIZE;
>
> -       ret = __block_write_begin(page, 0, end, get_block);
> -       if (!ret)
> -               ret = block_commit_write(page, 0, end);
> +       err = __block_write_begin(page, 0, end, get_block);
> +       if (!err)
> +               err = block_commit_write(page, 0, end);
>
> -       if (unlikely(ret < 0))
> +       if (unlikely(err < 0))
>                 goto out_unlock;
>         set_page_dirty(page);
>         wait_for_stable_page(page);
>         return 0;
>  out_unlock:
>         unlock_page(page);
> -       return ret;
> +       return block_page_mkwrite_return(err);
>  }
>  EXPORT_SYMBOL(block_page_mkwrite);
>
> diff --git a/fs/nilfs2/file.c b/fs/nilfs2/file.c
> index c5fa3de..da2759e 100644
> --- a/fs/nilfs2/file.c
> +++ b/fs/nilfs2/file.c
> @@ -57,7 +57,8 @@ static int nilfs_page_mkwrite(struct vm_fault *vmf)
>         struct page *page = vmf->page;
>         struct inode *inode = file_inode(vma->vm_file);
>         struct nilfs_transaction_info ti;
> -       int ret = 0;
> +       vm_fault_t ret = VM_FAULT_LOCKED;
> +       int err = 0;
>
>         if (unlikely(nilfs_near_disk_full(inode->i_sb->s_fs_info)))
>                 return VM_FAULT_SIGBUS; /* -ENOSPC */
> @@ -67,7 +68,7 @@ static int nilfs_page_mkwrite(struct vm_fault *vmf)
>         if (page->mapping != inode->i_mapping ||
>             page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
>                 unlock_page(page);
> -               ret = -EFAULT;  /* make the VM retry the fault */
> +               ret = VM_FAULT_NOPAGE;  /* make the VM retry the fault */
>                 goto out;
>         }
>
> @@ -99,10 +100,12 @@ static int nilfs_page_mkwrite(struct vm_fault *vmf)
>         /*
>          * fill hole blocks
>          */
> -       ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
> +       err = nilfs_transaction_begin(inode->i_sb, &ti, 1);
>         /* never returns -ENOMEM, but may return -ENOSPC */
> -       if (unlikely(ret))
> +       if (unlikely(err)) {
> +               ret = block_page_mkwrite_return(err);
>                 goto out;
> +       }
>
>         file_update_time(vma->vm_file);
>         ret = block_page_mkwrite(vma, vmf, nilfs_get_block);
> @@ -117,7 +120,7 @@ static int nilfs_page_mkwrite(struct vm_fault *vmf)
>         wait_for_stable_page(page);
>   out:
>         sb_end_pagefault(inode->i_sb);
> -       return block_page_mkwrite_return(ret);
> +       return ret;
>  }
>
>  static const struct vm_operations_struct nilfs_file_vm_ops = {
> diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
> index ed7a81b..7184c6e 100644
> --- a/include/linux/buffer_head.h
> +++ b/include/linux/buffer_head.h
> @@ -240,7 +240,7 @@ int cont_write_begin(struct file *, struct address_space *, loff_t,
>                         get_block_t *, loff_t *);
>  int generic_cont_expand_simple(struct inode *inode, loff_t size);
>  int block_commit_write(struct page *page, unsigned from, unsigned to);
> -int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
> +vm_fault_t block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
>                                 get_block_t get_block);
>  /* Convert errno to return value from ->page_mkwrite() call */
>  static inline vm_fault_t block_page_mkwrite_return(int err)
> --
> 1.9.1
>